API Reference¶

All public symbols are exported from the pyswarm package.

Exported symbols¶

• pso

pso¶

pso(func, lb, ub, ...)¶

Minimize an objective function using Particle Swarm Optimization.

pso(
    func,
    lb,
    ub,
    ieqcons=None,
    f_ieqcons=None,
    args=(),
    kwargs=None,
    swarmsize=100,
    omega=0.5,
    phip=0.5,
    phig=0.5,
    maxiter=100,
    minstep=1e-8,
    minfunc=1e-8,
    debug=False,
    processes=1,
    particle_output=False,
)

Required arguments¶

func : Callable objective function to minimize. It receives the current candidate vector as the first argument and returns a scalar objective value.

lb : Lower bounds for each design variable.

ub : Upper bounds for each design variable.

Optional arguments¶

ieqcons : List of constraint functions. Each function must return a value greater than or equal to 0.0 for a feasible candidate. If f_ieqcons is provided, this list is ignored.

f_ieqcons : A single constraint function returning a 1-D array-like object. Every returned value must be greater than or equal to 0.0 for a feasible candidate.

args : Additional positional arguments passed to the objective and constraint functions.

kwargs : Additional keyword arguments passed to the objective and constraint functions.

swarmsize : Number of particles in the swarm. Default: 100.

omega : Particle velocity scaling factor. Default: 0.5.

phip : Scaling factor for movement toward each particle's best known position. Default: 0.5.

phig : Scaling factor for movement toward the swarm's best known position. Default: 0.5.

maxiter : Maximum number of iterations. Default: 100.

minstep : Minimum step size of the swarm's best position before the search terminates. Default: 1e-8.

minfunc : Minimum change in the swarm's best objective value before the search terminates. Default: 1e-8.

debug : If True, prints progress information during optimization. Default: False.

processes : Number of processes used to evaluate the objective and constraints. Default: 1.

particle_output : If True, returns per-particle best positions and objective values in addition to the swarm best. Default: False.

Returns¶

By default, pso returns:

xopt : The swarm's best known position.

fopt : The objective value at xopt.

If particle_output=True, it also returns:

p : The best known position per particle.

pf : The objective values at each position in p.

Raises¶

TypeError : Raised when func is not callable.

ValueError : Raised when lower and upper bounds have different lengths or when any upper bound is not greater than its corresponding lower bound.

Constraint conventions¶

Constraints are feasible when they are non-negative:

def constraint(x):
    return [limit - measured_value]

Use f_ieqcons when one function returns all constraint values. Use ieqcons when each constraint is its own scalar function.

References¶

See References for full citations.